Liquid Crystal Displays (LCD) are characterized by a backlight source for generating an image. The backlight is transmitted through an array of pixels filled with liquid crystal materials. Each pixel is electrically controlled. The applied electrical voltage across a pixel defines the amount of light transmitted through the pixel. The amount of light which is transmitted from the backlight source through the liquid crystal pixel may range from zero, which produces a black pixel, to 255 which produces the whitest pixel. The backlight source in an LCD structure is a heavy power consumer. On the other hand, changing the pixel opacity consumes relatively low zero power consumption. There are known techniques to save backlight power by measuring the surrounding ambient light and then adjusting the BLIL (Backlight level) accordingly. Another approach for managing a LCD's backlight in order to reduce power consumption is by measuring or monitoring user's activity so that BLIL is reduced when the user appears to be less active. In all these prior art solutions there is likely a quality deterioration of the image presented to the user and therefore a significant reduction in the overall user's experience. Most of these power saving solutions are directed to inactive states of the screen while high power is still consumed during active states of the screen e.g. watching a video or playing games.
In a typical color LCD, each pixel is composed of three sub-pixels of RGB. The appearance of each pixel to a user's eyes, its color and brightness, is a function of the backlight of the pixel and its opacity value. Content Adaptive Backlight Control (CABC) is known in the art. CABC results in a dimmed backlight and a boosted pixel value to increase its opacity in order to save power and achieve a perceived pixel as intended to be achieved by the original image. Known in the art are 0, 1 and 2 dimensional backlight control. In addition, image histogram analysis is known in order to define the whitest point to display. However, with reduced backlight comes the cost of reduced dynamic range for the pixel. This may lead to artifacts such as clipped pixels or washout when higher brightness is required but can't be produced.
One solution known in the prior art to avoid washout of pixels is to analyze the whites point for each color separately and use the whitest point among all colors as the most upper brightness limit to be practiced. In addition, changing the BLL while an application is running may lead to flickering artifacts.
Another issue relevant to the known systems is that adjustments are made on an overall basis across different applications (such as games) and not keyed to the particular needs of an application or game on an individual basis. This may result in inefficient adjustments of BLIL and pixel values and may not efficiently reduce power consumption. Therefore, there is a need to have a CABC and pixel value control system that conserves power and which is keyed to the individual application, program or game being played at any given time that reduces artifacts while minimizing original image quality deterioration. In addition, there is a need for a system and method which facilitates the background processing of individual applications and games for the “best” balance of BLIL and pixel values offline so that the mobile device does not consume excessive power in “real time” while, for example, a game is being played. It is to address these issues that the present application is directed.